The present invention relates to the field of surgical apparatus and more specifically, to a suture and associated anchoring mechanism for applying tissue retraction during surgery.
Generally, surgery requires an incision through a patient""s skin, underlying muscle and tissue to expose the underlying body organ or anatomical tissue which is in need of the particular surgical intervention. In certain types of surgery such as cardiac surgery for instance, the patient""s bone structure may also be incised and retracted. This is the case with a midline sternotomy incision which incises the patient""s sternum and retracts the ribcage, or in situations where bone structure is spread apart without incision thereof as with an intercostal thoracotomy incision in which two adjacent patient ribs are spread apart in order to expose the underlying body organ, namely the patient""s heart.
To obtain and maintain a surgical window or opening onto the underlying body organ or tissue in relation to which the surgical intervention will take place, abdominal or thoracic surgical retractors are used subsequent to the initial incision to spread the incised body tissue. Surgical retractors exist in many sizes and shapes and have been present since the dawn of surgery. Most known retractors have an elongate rack bar and two retracting arms, namely a fixed retracting arm and a movable retracting arm. Both arms typically extend in a direction normal to the rack bar. The movable arm can be displaced along the rack bar, and relative to the fixed arm, by using a crank to activate a pinion mechanism which engages teeth on the rack bar. Two blades are provided, usually disposed below the retractor arm and extending into the surgical incision, to interface with the patient""s skin and tissue and to apply the retraction that creates the surgical window by relative movement and an ensuing spacing apart of the two retractor arms. The retractor blades may also engage with the patient""s bone structure during surgery that requires access to tissue or organs contained within the patient""s thorax. This is the case with coronary artery bypass graft (CABG) surgery, where the patient""s skin and incised sternum are engaged with the blades of a surgical retractor known as a sternum or sternal retractor. The basic surgical approach and surgical retractor design for creating a surgical window onto the underlying tissue and organs requiring the surgical intervention, whereby the two or more spreader members or retractor arms are moved apart to retract engaged tissue, have remained relatively unchanged since the first introduction of retractors to surgery, regardless of the type, size and shape of the surgical retractor. The surgeon may at times place a sterile drape, cloth, or other type of packing between the patient""s incised body tissue and the interfacing blades or other portion of the surgical retractor.
Once the surgical window is created, the surgeon often times will retract other internal body tissue which becomes accessible through the surgical window, with a flexible wire-like filament having a tissue-piercing member on one end of the wire-like filament, such as a suture line with integral needle on one end of the suture line. The suture line with the integral tissue piercing needle at one end will be referred to herein as the xe2x80x9ctraditional suturexe2x80x9d or simply the xe2x80x9csuturexe2x80x9d.
A standard technique for retraction of coronary tissue during cardiac surgery has been the use of sutures, including traction sutures and stay sutures. These sutures are well known in the field of cardiac surgery and are available in a variety of needle configurations, suture length and diameter thicknesses. The sutures are generally available in kit form in disposable sterilized packets containing a needle and a length of filament.
Internal body tissue may be retracted for a number of reasons during surgery, namely:
a) to improve access to the target body organ or target organ tissue requiring the surgical intervention; this may be accomplished by displacing or retracting surrounding internal body tissue that may obstruct, restrict or impede surgical access, as for instance when retracting fatty tissue;
b) to maintain access to the inside of an organ cavity or body vessel subsequent to an incision of the organ or vessel; this may be accomplished by retracting incised portions of organ tissue or vessel tissue, as for instance when retracting incised portions of the aorta to maintain access to the aortic valve;
c) to position or orient at least a portion of the body organ; this may be accomplished through retraction of surrounding tissue which is anatomically attached to the body organ or through retraction of the body organ directly.
Tissue retraction is typically achieved by piercing the body organ or body tissue with a needle at the end of a suture line, threading a length of suture line through the pierced body tissue, and pulling simultaneously on both resulting lengths of the suture line; that is, the length between the pierced tissue and the free end of the suture line, and the length between the pierced tissue and the needle-bearing end of the suture line. Retraction loads are imposed on the body tissue or body organ at the location where the needle pierces and penetrates through the tissue or the organ.
In most surgical procedures, retraction is maintained by securing the above mentioned two lengths of the suture line by accomplishing one of the following techniques:
a) tying the free end and needle-bearing end of the suture line to each other through another part of the patient""s anatomy, preferably remote to the location of body tissue where the surgical intervention will take place;
b) simultaneously clamping these two lengths of suture line to other body tissue or to the sterile cloth or packing inserted between the surgical retractor and the patient""s incised tissue creating the surgical window;
c) clamping these two lengths to the surgical retractor with a surgical clamp or tying the free end and the needle-bearing end of these two lengths to each other and to a portion of the surgical retractor;
d) clamping these two lengths with a surgical clamp and wedging the tip or at least a portion of the surgical clamp between the retractor and the patient""s body or between the retractor and the sterile cloth or packing placed along the surgical incision and trapped between the retractor blades and patient""s body.
The current methods described above of maintaining tissue retraction may, in some instances:
a) be time consuming, since securing of the retraction load through the manual tying of the suture line lengths is a multi-step threading and knotting procedure,
b) be cumbersome due to poor access during the manual tie down of the suture line lengths, especially in surgical interventions when the surgical window is small;
c) not be conducive to readjustment of the magnitude of the desired tensile retraction load on the organ or body tissue, or on the direction of said load relative to the organ or body tissue without having to untie and retie suture line lengths or without having to cut the existing suture line having the undesired retraction load and replacing it with a new suture that must again pierce the organ or body tissue and be secured by way of one of the methods listed above;
d) compromise the ergonomics of and the surgeon""s access into the surgical window, especially when a surgical clamp is used to secure the two lengths of the suture line to the perimeter of the surgical window or to a portion of the surgical retractor used to create the surgical window, all the more when multiple suture lines need to be secured to achieve the desired organ or body tissue retraction;
e) hinder or restrict the readjustment of the surgical window opening through the opening or closing of the surgical retractor, if the lengths of the suture line are tied to the rack bar of the surgical retractor, or hinder the deployment or readjustment of peripheral surgical devices that are mounted or need to be mounted on the spreader arms of the retractor.
Generally, adjustment of the desired tensile retraction by cutting an existing suture line and repiercing a new suture line is not desirable. First, the process of placing a suture requires considerable manual dexterity, at times requiring the help of an assistant. The process is therefore tedious and time consuming. Second, a repiercing of the internal body tissue or body organ with a, subsequent suture tends to increase the likelihood of inducing tissue trauma or tissue tearing which may have to be surgically repaired.
More recently with the advent of minimally invasive surgical techniques, laparoscopic approaches have been developed. Consequently, the surgical access windows into the patient""s abdomen or thorax have become smaller. However, internal tissue retraction through a suture (suture line with a tissue piercing needle attached to at least one end) remains a requirement in certain types of surgical interventions. This tissue retraction with suture tends to generally be more difficult due to the smaller access through a laparoscopic entry relative to the larger surgical access window obtained through the traditional retracted incision entry.
Although the principles of this invention may be applied to many types of surgeries requiring tissue retraction by the application and maintenance of a tensile load on a suture, the examples will focus on cardiac surgery; and more specifically, on CABG surgery performed on the beating heart. In addition, although the examples will refer to retraction of internal body tissue, the concepts and principles may also be extended to external body tissue, as those skilled in this art will appreciate.
CABG surgery has been traditionally performed with the support of the cardio-pulmonary machine, whereby the patient""s blood is oxygenated outside the body through extracorporeal circulation (ECC). This allows the surgeon to manipulate and operate on a perfectly still heart. During traditional CABG surgery, the surgeon or assistant can manually position and orient the arrested heart for best access to the target artery requiring the bypass graft.
Recently, in an aim to render CABG surgery less invasive to the patient, beating heart CABG surgery is being developed whereby ECC, one of the most invasive aspects of cardiac surgery, is eliminated and coronary artery revascularization is performed directly on the beating heart. One of the challenges in performing beating heart CABG surgery lies in positioning and orienting the beating heart in order to obtain access to the inferior and posterior artery beds, while tending to minimize physiologically undesirable effects such as hemodynamic instability, arrhythmia, or a precipitous drop in arterial pressure, that may occur as a result of such manipulations. In traditional CABG surgery the heart is arrested and therefore heart manipulations are well tolerated.
During CABG surgery or beating heart CABG surgery, the pericardium, namely the membranous sac in which the heart and the commencement of the major blood vessels connecting with the heart are contained, is generally incised and unraveled to expose at least a portion of the heart surface which is to receive the bypass graft. The pericardium tissue, unlike the heart, is not beating and can be separated from the heart surface except in some locations where it is anatomically attached to the heart. Thus, it is surgically possible to position or orient the heart by manipulating the pericardium tissue to which it is attached. In beating heart CABG surgery, it may be desirable to position and orient the beating heart through retraction of the pericardium tissue to obtain access to the inferior and posterior coronary artery beds. The likelihood of inducing trauma to the beating heart tends to be reduced, and the physiologically undesirable effects mentioned above tend to be reduced, since direct contact with the beating heart is avoided and the manipulations are achieved through retraction of the pericardium tissue which, although incised remains anatomically attached to the beating heart in certain locations.
Based on the foregoing, it would therefore be advantageous to provide a suture with an integral anchoring member that may be inserted into an anchoring port of a stable platform (such as a surgical retractor) to tend to achieve and maintain the desired tissue retraction load on the organ or body tissue of the patient in a relatively quicker and more convenient fashion than some of the prior art methods described above.
Alternatively, based on the foregoing, it would also be advantageous to provide a surgical retractor configured with an integral suture anchoring mechanism or add-on suture anchoring mechanism capable of engaging a traditional suture (namely, as explained above, a suture comprised of a suture line with tissue piercing needle attached to at least one end) to tend to achieve and maintain the desired tissue retraction load on the organ or body tissue of the patient in a relatively quicker and more convenient fashion than some of the current methods described above.
Thus it is one of the objects of the present invention to aim to reduce deployment times associated to the placement of tissue retraction sutures and to facilitate the securement thereof during surgery.
It is another object of the present invention to provide a tissue retractor comprising a suture line allowing the retraction of body tissue or body organs during the surgical intervention that aims to eliminate the operation of manually tying suture line lengths to one another through a multi-step threading and knotting procedure in order to achieve the said retraction.
It is another object of the present invention to provide a tissue retractor comprising a suture line allowing the retraction of internal body tissue or body organs during the surgical intervention which permits the readjustment of the retraction force applied by said suture line to the internal body tissue, either in magnitude or in direction, without requiring the severing or disposal of said suture line and without the removal of said suture line from internal body tissue.
These and other objects of the present invention will become apparent from the description of the present invention and its preferred embodiments which follows.
According to one broad aspect of the present invention, there is provided a tissue retractor for displacing body tissue during surgery, the tissue retractor comprising a surgical tissue piercing member; a suture line affixed to the surgical tissue piercing member; a fixed element, the fixed element being associated with a stable surgical platform; a movable element, the moveable element cooperating with the fixed element to engage a portion of the suture line after the suture line is threaded through the body tissue with the surgical tissue piercing member and after the threaded suture line is tensioned to effect a predetermined displacement of said body tissue; and wherein said perdetermined displacement of said body tissue is maintained by retention of the engaged portion of the suture line by the movable element and the fixed element.
In some surgical interventions, the foregoing features contribute to attempt to position and orient the beating heart through retraction of the incised pericardium tissue during beating heart CABG, while tending to minimize the likelihood of inducing physiologically adverse effects such as hemodynamic instability, arrhythmia, or a precipitous drop in arterial pressure.